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| PLT03 | Energy Recovery Linac Experimental Challenges | photon, emittance, undulator, optics | 7 | ||||
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ERL projects are ongoing at Jlab, Daresbury, KEK and Cornell. Here we describe the typical experimental concerns of using high-coherence and ultra-fast pulses from the Cornell ERL as an example of a new opportunities. The hi-flux mode is one where the ERL runs at 5 GeV and 100 mA. Many experiments are photon-starved, such as inelastic X-ray scattering. The high-coherence mode is obtained at 25 mA and the transverse emittances could be as low as 8 pm. The beam size will be at its smallest under this operating condition and average spectral brightness as high as 1023 (standard units) are calculated. (WG2 will discuss the ERL accelerator issues.) We expect to produce a 3 micron round emitting source for imaging and coherence experiments on individual biological cells. The ultra-fast mode is one obtained by reducing the repetition rate to 1 MHz and by increasing the bunch charge to 1 nC per pulse and compressing the natural 2 ps bunch length to less than 100 fs. We will present science opportunities for X-ray experiments on a single atom as well as the challenges in optics, other experiments, and beam control issues when making a 1 nm focused X-ray beam size.
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| WG313 | Beam Physics Highlights of the FERMI@ELETTRA Project | emittance, electron, simulation, laser | 27 | ||||
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The electron beam dynamics in the Fermi Linac has been studied in the framework of the design of a single-pass free electron laser (fel) based on a seeded harmonic cascade. The wakefields of some accelerating sections represent a challenge for the preservation of a small beam emittance and for achieving a small final energy spread. Various analytical techniques and tracking codes have been employed in order to minimize the quadratic and the cubic energy chirps in the longitudinal phase space, since they may cause a degradation of the fel bandwidth. As for the transverse motion, the beam breakup (bbu) instability has been recognized as the main source of emittance dilution; the simulations show the validity of local and non-local correction methods in order to counteract the typical “banana” shape distortion of the beam caused by the instability.
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| WG322 | Status of the SPARX FEL Project | emittance, brightness, electron, simulation | 30 | ||||
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SPARX is a proposal for a X-ray-FEL facility jointly funded by MIUR (Research Department of Italian Government), Regione Lazio, CNR, ENEA, INFN and Rome University Tor Vergata. It is the natural extension of the ongoing activities of the SPARC collaboration. The aim is the generation of electron beams characterized by ultra-high peak brightness at the energy of 1 and 2 GeV, for the first and the second phase respectively. The beam is expected to drive a single pass FEL experiment in the range of 13.5–6 nm and 6–1.5 nm, at 1 GeV and 2 GeV respectively, both in SASE and SEEDED FEL configurations. A hybrid scheme of RF and magnetic compression will be adopted, based on the expertise achieved at the SPARC [1] high brightness photoinjector presently under installation at Frascati INFN-LNF Laboratories. The use of superconducting and exotic undulator sections will be also exploited. In this paper we discuss the present status of the collaboration.
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on behalf of the SPARX team |
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| WG324 | Single Bunch Emittance Preservation in XFEL Linac | emittance, quadrupole, booster, single-bunch | 33 | ||||
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The single bunch emittance preservation in booster and main linacs of European XFEL project is presented. The wakefield and chromatic dilution of the beam emittance caused by free betatron oscillations, cavity and modules offset misalignments and random tilts are evaluated. The effects of cavities misalignments correlation along the linac are discussed. The effects of quadrupole misalignments and the corresponding trajectory steering based on one-to-one correction technique are given. The residual chromatic emittance dilution of the corrected trajectory is evaluated.
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| WG512 | Longitudinal Diagnostics with THz Radiation | radiation, diagnostics, electron, synchrotron | 48 | ||||
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According to the FEL theory, the longitudinal charge distribution in an electron bunch has an important effect on lasing process. For FLASH at DESY, structures in the order of 10 μm play a crucial role in SASE production. The investigation of the electron bunch longitudinal charge distribution and its bunch to bunch changes is one of the most important issues for optimizing the operation of the machine and improving its stability. Single shot spectroscopic in the 10–200 μm regime is beyond the capability of existing spectroscopic diagnostic tools. This paper introduces a new diagnostics method based on fast spectrally resolved detection of coherent infrared radiation from electron bunches. Measurement results at FLASH with this spectrometer in both scanning mode and single shot mode are presented and discussed.
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